Air Pollution Impacts

Mount Rainier National Park

Natural and scenic resources in Mount Rainier National Park (NP) are susceptible to the harmful effects of air pollution. Nitrogen, mercury, ozone, and fine particles impact natural resources such as lakes, streams, fish, and vegetation, and scenic resources such as visibility. Click on the tabs below to learn more about air pollutants and their impacts on natural and scenic resources at Mount Rainier NP.

Nitrogen & Sulfur

Toxics & Mercury

Ozone

Visibility

How much nitrogen is too much?

Nitrogen is a fertilizer and some nitrogen is necessary for plants to grow. However, in natural ecosystems, too much nitrogen disrupts the balance of plant and aquatic communities, allowing weed species to grow faster. In some areas of Washington State, including the Columbia River Gorge and the Willamette Valley, high levels of nitrogen deposition have changed lichen communities. In those areas, lichens adapted to low nitrogen conditions are being replaced by lichens adapted to a more disturbed, polluted environment (Geiser and Neitlich 2007; Geiser et al. 2010). Surveys near Mount Rainier NP have found that the lichen communities are little affected by current nitrogen deposition rates. However, lichens can serve as an early warning system if nitrogen deposition increases. Similarly, the composition of sensitive aquatic communities can provide early warning signs of nitrogen deposition effects to waterbodies.

Nitrogen and sulfur compounds deposited from air pollution may harm lakes, streams, soils, and vegetation in Mount Rainier NP. High elevation ecosystems in the park are sensitive to nitrogen and sulfur deposition. Not only do these systems receive more atmospheric deposition than lower elevation areas, but short growing seasons and shallow soils limit the capacity of soils and plants to absorb nitrogen, and dilute surface waters cannot buffer the effects of acid deposition.

Spring snowmelt, late summer storms, or rain-on-snow events can cause highly acidic deposition events which could have detrimental effects on aquatic life and amphibians (Clow and Campbell 2008 [pdf, 2.1 MB]);

Episodic acidification of Eunice Lake, one of many lakes in the park sensitive to acidification (Samora and Clow 2002);

The chemistry of cloud water samples taken at the park indicate some of the lowest levels of pH and highest levels of acidity of any taken in the state (Basabe et al. 1989a).

Toxics, including heavy metals like mercury, accumulate in the tissue of organisms and may alter key ecosystem processes. When mercury converts to methylmercury in the environment and enters the food chain, effects can include reduced reproductive success, impaired growth and development, behavioral abnormalities, reduced immune response, and decreased survival. Human activities have greatly increased the amount of mercury in the environment through processes such as burning coal for electricity and burning waste. Other toxic air contaminants of concern include pesticides, industrial by-products, and emerging chemicals. Some of these toxics are also known or suspected to cause cancer or other serious chronic health effects in humans and wildlife.

Effects of mercury and airborne toxics on ecosystems at Mount Rainier NP include:

Subalpine fir, a species sensitive to ozone injury at Mount Rainier NP, Washington.

Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants, and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.

Ozone is transported to Mount Rainier NP from the Puget Sound urban zone and via trans-Pacific air masses (Barna et al. 2000; Jaffe et al. 2003). While several park species including Abies lasiocarpa (subalpine fir) and Populus trichocarpa (black cottonwood) that are known to be sensitive to ozone (Brace et al. 1999) have been systematically evaluated, no ozone injury has been documented in the park.

Air pollutants can affect visibility at Mount Rainier NP, Washington (clear to hazy from top to bottom).

Many visitors come to Mount Rainier NP to enjoy stunning views of the fifth tallest peak in the contiguous 48 states, the highest in the chain of volcanoes comprising the Cascade Range. Unfortunately, these vistas are often obscured by haze caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze and visibility impairment. Organic compounds, soot, and dust reduce visibility as well.

Visibility effects at Mount Rainier NP include:

Reduction of the average natural visual range from about 140 miles (without the effects of pollution) to about 65 miles because of pollution at the parks;

Reduction of the visual range from about 100 miles to below 40 miles on high pollution days;